Spectroscopy and photophysics of 9-methylalloxazine. Experimental and theoretical study

Sikorska, Ewa; Khmelinskii, Igor; Prukała, Wiesław; Williams, Siân L.; Worrall, David R.; Bourdelande, J. L.; Bednarek, Aneta; Koput, Jacek; Sikorski, Marek

doi:10.1016/j.molstruc.2003.10.028

Cited by 10 publications

(3 citation statements)

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“…44 Time-dependent densityfunctional theory has been successfully applied to a number of iso-and alloxazines to predict ground state and triplet-triplet electronic absorption spectra with good correspondence to the measured transitions. 30,31,[44][45][46][47][48][49] The present paper describes a steady-state and time-resolved study on the ESDPT reaction in lumichrome and its 1-and 3-methyl and 1,3-dimethyl derivatives in ethanolic solutions. We also report quantum mechanical calculations that shed new light on the mechanism of the ESDPT reaction in the lumichrome/carboxylic acid systems.…”

Section: Introductionmentioning

confidence: 99%

“…Spectral and photophysical properties of lumichrome in a number of different protic and aprotic and polar and nonpolar solvents have been examined recently . Time-dependent density-functional theory has been successfully applied to a number of iso- and alloxazines to predict ground state and triplet−triplet electronic absorption spectra with good correspondence to the measured transitions. ,,− …”

Section: Introductionmentioning

confidence: 99%

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Ground- and Excited-State Double Proton Transfer in Lumichrome/Acetic Acid System: Theoretical and Experimental Approach

et al. 2005

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Experimental time-resolved spectral and photon counting kinetic results confirm formation of an isoalloxazinic excited state via excited-state double proton transfer (ESDPT) catalyzed by a carboxylic acid molecule that forms a hydrogen-bond complex with the parent alloxazine molecule. This isoalloxazinic tautomer manifests itself as a distinct long-lived emissive species formed only in such alloxazine derivatives that were not substituted at the N1 nitrogen atom, being a product of the excited-state reaction occurring from the alloxazinic excited state. Theoretical calculations support the idea that the ESDPT occurs by the concerted mechanism. The calculated activation barrier in the excited state is much lower than the same barrier in the ground state and even disappears for the HOMO-1 to LUMO excitation, which explains the fact that the reaction takes place in the excited-state only. The reaction rate estimated from the emission kinetics is ca. 1.4 x 10(8) dm3 mol(-1) s(-1) in ethanolic solutions of lumichrome with added acetic acid.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ground- and Excited-State Double Proton Transfer in Lumichrome/Acetic Acid System: Theoretical and Experimental Approach

et al. 2005

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“…The lower energy absorption bands around 355 and 385 nm, have been well reproduced using diverse theoretical methods in gas phase and different solvents (4,26,27,39,40,(75)(76)(77)(78). However, the agreement between the theoretical and experimental transition energies is poor in the UV-C region.…”

Section: Electronic Structurementioning

confidence: 95%

Initial Excited State Dynamics of Lumichrome upon Ultraviolet Excitation

Ghosh

Puranik

2022

Photochem & Photobiology

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Lumichrome (LC) is the major photodegradation product of biologically important flavin cofactors. Since LC serves as a structural comparison with the flavins; understanding excited states of LC is fundamentally important to establish a connection with photophysics of different flavins, such as lumiflavin (LF), riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). Herein, we deduce the initial excited state structural dynamics of LC using UV resonance Raman (UVRR) intensity analysis. The UVRR spectra at wavelengths across the 260 nm absorption band of LC were measured and resulting Raman excitation profiles and absorption spectrum were self‐consistently simulated using a time‐dependent wave packet formalism to extract the initial excited state structural and solvent broadening parameters. These results are compared with those obtained for other flavins following UV excitations. We find that LC undergoes a very distinct instantaneous charge redistribution than flavins, which is attributed to the extended π‐conjugation present in flavins but missing in LC. The homogeneous broadening linewidth of LC appears to be lower than that of LF, while the inhomogeneous broadening values are comparable, indicating greater solvent interaction with excited flavin on ultrafast timescale compared with LC, whereas on longer timescale these interactions are almost similar.

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